From: Rusty Russell <rusty@rustcorp.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: xen-devel@lists.xensource.com, Jeff Garzik <jeff@garzik.org>,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
virtualization@lists.osdl.org, linux-kernel@vger.kernel.org,
Chris Wright <chrisw@sous-sol.org>,
Ian Pratt <ian.pratt@xensource.com>
Subject: Re: [RFC PATCH 35/35] Add Xen virtual block device driver.
Date: Sat, 25 Mar 2006 21:03:11 +1100 [thread overview]
Message-ID: <1143280992.8228.12.camel@localhost.localdomain> (raw)
In-Reply-To: <1143215728.18986.15.camel@localhost.localdomain>
On Fri, 2006-03-24 at 15:55 +0000, Alan Cox wrote:
> On Gwe, 2006-03-24 at 07:38 -0500, Jeff Garzik wrote:
> > > A pure SCSI abstraction doesn't allow for shared head scheduling which
> > > you will need to scale Xen sanely on typical PC boxes.
> >
> > Not true at all. If you can do it with a block device, you can do it
> > with a SCSI block device.
>
> I don't believe this is true. The complexity of expressing sequences of
> command ordering between virtual machines acting in a co-operative but
> secure manner isn't as far as I can see expressable sanely in SCSI TCQ
I thought usb_scsi taught us that SCSI was overkill for a block
abstraction? I have a much simpler Xen block-device implementation
which seems to perform OK, and is a lot less LOC than the in-tree one,
so I don't think the "SCSI would be better than what's there" (while
possibly true) is valid.
Cheers!
Rusty.
--
ccontrol: http://ozlabs.org/~rusty/ccontrol
WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jeff Garzik <jeff@garzik.org>, Chris Wright <chrisw@sous-sol.org>,
xen-devel@lists.xensource.com,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
Ian Pratt <ian.pratt@xensource.com>,
virtualization@lists.osdl.org, ian.pratt@cl.cam.ac.uk,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 35/35] Add Xen virtual block device driver.
Date: Sat, 25 Mar 2006 21:03:11 +1100 [thread overview]
Message-ID: <1143280992.8228.12.camel@localhost.localdomain> (raw)
In-Reply-To: <1143215728.18986.15.camel@localhost.localdomain>
On Fri, 2006-03-24 at 15:55 +0000, Alan Cox wrote:
> On Gwe, 2006-03-24 at 07:38 -0500, Jeff Garzik wrote:
> > > A pure SCSI abstraction doesn't allow for shared head scheduling which
> > > you will need to scale Xen sanely on typical PC boxes.
> >
> > Not true at all. If you can do it with a block device, you can do it
> > with a SCSI block device.
>
> I don't believe this is true. The complexity of expressing sequences of
> command ordering between virtual machines acting in a co-operative but
> secure manner isn't as far as I can see expressable sanely in SCSI TCQ
I thought usb_scsi taught us that SCSI was overkill for a block
abstraction? I have a much simpler Xen block-device implementation
which seems to perform OK, and is a lot less LOC than the in-tree one,
so I don't think the "SCSI would be better than what's there" (while
possibly true) is valid.
Cheers!
Rusty.
--
ccontrol: http://ozlabs.org/~rusty/ccontrol
next prev parent reply other threads:[~2006-03-25 10:03 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-22 16:52 [RFC PATCH 35/35] Add Xen virtual block device driver Ian Pratt
2006-03-22 16:52 ` Ian Pratt
2006-03-22 17:09 ` Anthony Liguori
2006-03-22 17:09 ` Anthony Liguori
2006-03-22 23:09 ` Jeff Garzik
2006-03-24 12:17 ` Alan Cox
2006-03-24 12:38 ` Jeff Garzik
2006-03-24 13:37 ` Jeff Garzik
2006-03-24 13:40 ` Arjan van de Ven
2006-03-24 13:50 ` Jeff Garzik
2006-03-24 15:33 ` Dave C Boutcher
2006-03-24 19:04 ` Mike Christie
2006-03-24 19:04 ` Mike Christie
2006-03-24 19:19 ` Dave C Boutcher
2006-03-25 0:32 ` FUJITA Tomonori
2006-03-25 0:47 ` Roland Dreier
2006-03-25 0:47 ` Roland Dreier
2006-03-24 15:55 ` Alan Cox
2006-03-24 15:55 ` Alan Cox
2006-03-25 10:03 ` Rusty Russell [this message]
2006-03-25 10:03 ` Rusty Russell
2006-03-27 10:14 ` Peter Chubb
2006-03-23 8:19 ` Arjan van de Ven
2006-03-23 9:34 ` Keir Fraser
2006-03-23 9:34 ` Keir Fraser
2006-03-23 9:41 ` Arjan van de Ven
2006-03-23 9:42 ` Arjan van de Ven
-- strict thread matches above, loose matches on Subject: below --
2006-05-09 8:49 [RFC PATCH 00/35] Xen i386 paravirtualization support Chris Wright
2006-05-09 7:00 ` [RFC PATCH 35/35] Add Xen virtual block device driver Chris Wright
2006-05-09 12:01 ` Christoph Hellwig
2006-03-22 6:30 [RFC PATCH 00/35] Xen i386 paravirtualization support Chris Wright
2006-03-22 6:31 ` [RFC PATCH 35/35] Add Xen virtual block device driver Chris Wright
2006-03-22 16:39 ` Anthony Liguori
2006-03-22 16:54 ` Christoph Hellwig
2006-03-27 8:42 ` Gerd Hoffmann
2006-03-27 8:42 ` Gerd Hoffmann
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